/* Copyright (c) 2013 Coraid, Inc.  See COPYING for GPL terms. */
/*
 * aoenet.c
 * Ethernet portion of AoE driver
 */

#include <linux/gfp.h>
#include <linux/hdreg.h>
#include <linux/blkdev.h>
#include <linux/netdevice.h>
#include <linux/moduleparam.h>
#include <net/net_namespace.h>
#include <linux/unaligned.h>
#include "aoe.h"

#define NECODES 5

static char *aoe_errlist[] =
{
        "no such error",
        "unrecognized command code",
        "bad argument parameter",
        "device unavailable",
        "config string present",
        "unsupported version"
};

enum {
        IFLISTSZ = 1024,
};

static char aoe_iflist[IFLISTSZ];
module_param_string(aoe_iflist, aoe_iflist, IFLISTSZ, 0600);
MODULE_PARM_DESC(aoe_iflist, "aoe_iflist=dev1[,dev2...]");

static wait_queue_head_t txwq;
static struct ktstate kts;

#ifndef MODULE
static int __init aoe_iflist_setup(char *str)
{
        strscpy(aoe_iflist, str, IFLISTSZ);
        return 1;
}

__setup("aoe_iflist=", aoe_iflist_setup);
#endif

static spinlock_t txlock;
static struct sk_buff_head skbtxq;

/* enters with txlock held */
static int
tx(int id) __must_hold(&txlock)
{
        struct sk_buff *skb;
        struct net_device *ifp;

        while ((skb = skb_dequeue(&skbtxq))) {
                spin_unlock_irq(&txlock);
                ifp = skb->dev;
                if (dev_queue_xmit(skb) == NET_XMIT_DROP && net_ratelimit())
                        pr_warn("aoe: packet could not be sent on %s.  %s\n",
                                ifp ? ifp->name : "netif",
                                "consider increasing tx_queue_len");
                dev_put(ifp);
                spin_lock_irq(&txlock);
        }
        return 0;
}

int
is_aoe_netif(struct net_device *ifp)
{
        register char *p, *q;
        register int len;

        if (aoe_iflist[0] == '\0')
                return 1;

        p = aoe_iflist + strspn(aoe_iflist, WHITESPACE);
        for (; *p; p = q + strspn(q, WHITESPACE)) {
                q = p + strcspn(p, WHITESPACE);
                if (q != p)
                        len = q - p;
                else
                        len = strlen(p); /* last token in aoe_iflist */

                if (strlen(ifp->name) == len && !strncmp(ifp->name, p, len))
                        return 1;
                if (q == p)
                        break;
        }

        return 0;
}

int
set_aoe_iflist(const char __user *user_str, size_t size)
{
        if (size >= IFLISTSZ)
                return -EINVAL;

        if (copy_from_user(aoe_iflist, user_str, size)) {
                printk(KERN_INFO "aoe: copy from user failed\n");
                return -EFAULT;
        }
        aoe_iflist[size] = 0x00;
        return 0;
}

void
aoenet_xmit(struct sk_buff_head *queue)
{
        struct sk_buff *skb, *tmp;
        ulong flags;

        skb_queue_walk_safe(queue, skb, tmp) {
                __skb_unlink(skb, queue);
                spin_lock_irqsave(&txlock, flags);
                skb_queue_tail(&skbtxq, skb);
                spin_unlock_irqrestore(&txlock, flags);
                wake_up(&txwq);
        }
}

/*
 * (1) len doesn't include the header by default.  I want this.
 */
static int
aoenet_rcv(struct sk_buff *skb, struct net_device *ifp, struct packet_type *pt, struct net_device *orig_dev)
{
        struct aoe_hdr *h;
        struct aoe_atahdr *ah;
        u32 n;
        int sn;

        if (dev_net(ifp) != &init_net)
                goto exit;

        skb = skb_share_check(skb, GFP_ATOMIC);
        if (skb == NULL)
                return 0;
        if (!is_aoe_netif(ifp))
                goto exit;
        skb_push(skb, ETH_HLEN);        /* (1) */
        sn = sizeof(*h) + sizeof(*ah);
        if (skb->len >= sn) {
                sn -= skb_headlen(skb);
                if (sn > 0 && !__pskb_pull_tail(skb, sn))
                        goto exit;
        }
        h = (struct aoe_hdr *) skb->data;
        n = get_unaligned_be32(&h->tag);
        if ((h->verfl & AOEFL_RSP) == 0 || (n & 1<<31))
                goto exit;

        if (h->verfl & AOEFL_ERR) {
                n = h->err;
                if (n > NECODES)
                        n = 0;
                if (net_ratelimit())
                        printk(KERN_ERR
                                "%s%d.%d@%s; ecode=%d '%s'\n",
                                "aoe: error packet from ",
                                get_unaligned_be16(&h->major),
                                h->minor, skb->dev->name,
                                h->err, aoe_errlist[n]);
                goto exit;
        }

        switch (h->cmd) {
        case AOECMD_ATA:
                /* ata_rsp may keep skb for later processing or give it back */
                skb = aoecmd_ata_rsp(skb);
                break;
        case AOECMD_CFG:
                aoecmd_cfg_rsp(skb);
                break;
        default:
                if (h->cmd >= AOECMD_VEND_MIN)
                        break;  /* don't complain about vendor commands */
                pr_info("aoe: unknown AoE command type 0x%02x\n", h->cmd);
                break;
        }

        if (!skb)
                return 0;
exit:
        dev_kfree_skb(skb);
        return 0;
}

static struct packet_type aoe_pt __read_mostly = {
        .type = __constant_htons(ETH_P_AOE),
        .func = aoenet_rcv,
};

int __init
aoenet_init(void)
{
        skb_queue_head_init(&skbtxq);
        init_waitqueue_head(&txwq);
        spin_lock_init(&txlock);
        kts.lock = &txlock;
        kts.fn = tx;
        kts.waitq = &txwq;
        kts.id = 0;
        snprintf(kts.name, sizeof(kts.name), "aoe_tx%d", kts.id);
        if (aoe_ktstart(&kts))
                return -EAGAIN;
        dev_add_pack(&aoe_pt);
        return 0;
}

void
aoenet_exit(void)
{
        aoe_ktstop(&kts);
        skb_queue_purge(&skbtxq);
        dev_remove_pack(&aoe_pt);
}